The dead baby boy found shoved in the bag of a Herald Square Victoria’s Secret shoplifting suspect died of asphyxiation soon after being born alive at full term, two law-enforcement sources told The Post on Friday.

The grisly findings mean that the the baby’s mother, 17-year-old Tiona Rodriguez of Brooklyn, now faces homicide charges on top of the shoplifting rap she’d originally been busted on, a source said as the teen awaited arraignment at Manhattan Criminal Court.

Rodriguez has a two-year-old son at home and has been in custody since Thursday afternoon, when a security guard stopped her as she allegedly looted lingerie from the flagship store at 34th Street and Broadway.

The guard — who made the horrific discovery by looking in the foul-smelling bag while waiting for cops — held Rodriguez and her companion, Francis Estevez, until police came, a source said.

The boy’s tiny corpse was clean, as if he had been washed — or drowned, one source noted. But the smell emanating from it led cops to believe the baby had been dead for more than 24 hours.

“We are leaning toward homicide,” the source added.

A preliminary examination has determined the boy had been born alive and found no signs of external trauma, sources said.

Rodriguez had told police that she had a miscarriage, a source said.

“She said she had the baby yesterday,” another source said. “She said it was not full-term. She said she didn’t know what to do with it.”